LII THE SELJUK TURKS vast responsibilities of Empire, and his accession no means unchallenged. His uncle, Kaward, march Rei, and at Karaj, to the south of Hamadan, a desperate battle was fought which lasted for three days and three nights before the pretender was defeated. Meanwhile Altigin, the Khan of Samarcand, had invaded the Empire, and in another quarter Ibrahim of Ghazna captured his uncle, Othman ; but Ibrahim was pursued and routed by the Amir Gumushtigin, whose servant, Anushtigin, was destined to found the dynasty of the Khwarazm Shahs or Kings of Khiva. Supported by the Nizam-ul-Mulk, Malik Shah weathered all these storms of state, together with the rebellion of a brother, and five years after his accession he was in a position to extend still farther the bounds of the Empire. His generals subdued the greater part of Syria and Egypt in the west, while in the east they not only conquered Bokhara and Samarcand, but received tribute from the Prince of Kashgar, who was obliged to recognize Seljuk suzerainty on his coins. The internal prosperity of the Empire increased under the wise guidance of the Nizam-ul-Mulk. Among the stories related of the famous Vizier is one that illustrates both the extent of the Empire and his own efficiency. The Nizam-ul-Mulk, it is said, paid the boatmen on the Oxus by bills on Antioch, and the efficiency of his financial policy was proved by the fact that they were readily cashed. Science was fostered by the monarch, who, himself a man of culture, founded the observatory at Nishapur in which Omar Khayyam laboured with other scientists to compute the new era which Malik Shah inaugurated, and which was termed Jalali in his honour. Moreover, the dynasty maintained its virility. The Sultan was passionately fond of polo, so much so that he played a match at Baghdad the day after his arrival at the capital; he was equally fond of shooting and kept a record of his bags of game. Malik Shah was seldom at rest, but among the cities in the Empire his favourite residence was Isfahan, which afterwards became the capital of Persia under the Safayi dynasty. There he constructed fine buildings and laid out sumptuous gardens.